A standard twisting or spinning machine or other filament winding or unwinding machine normally has a battery of spindles each adapted to hold a single yarn package and rotatable about respective upright axes. As a rule the spindles are arranged in banks, that is in at least two parallel horizontal rows next to one another, with one bank being accessible from one side of the machine and the other bank being accessible from the other side.
Each spindle has a drive whorl, a barrel-shaped drive pulley, and all of the whorls of each bank are longitudinally aligned. They are driven by a flat belt has a stretch extending along each side of the machine and has an inner face engaging all of the respective whorls and an outer face that is engaged with idler wheels between the whorls. These idlers press the belt against the whorls for good force-transmitting contact. Such a drive is used because it makes it possible to stop a single spindle during servicing or reloading without having to shut down the whole machine.
As described in PCT application WO 84/02932 a single flat belt having one stretch along one side of the machine and another stretch along another side of the machine is deflected at each end of the machine over two rollers so that it has at each end a short transversely extensing straight stretch. A drive wheel carried directly on the output of a drive motor engages one of these transverse stretches. Such an arrangement requires that considerable space be left inside the machine for this drive motor.
In German patent document No. 2,204,593 there is on each side of the machine a flat tangential-type drive belt. A belt drive and a single motor drives both such flat belts. Such an arrangement is fairly complex and expensive and does not ensure accurate synchronization of movement of the two flat belts.